Road making and the like



United States Pate-r1120 ROAD MAKING AND THE LIKE Gilman B. Mollring,Los Angeles, Calif.

No Drawing. Application May 25, 1954, Serial No. 432,334

3 Claims. (Cl. 106-280) This invention relates to a method for buildingroads in which asphalt or other bituminous substances are employed tocoat and bind the mineral aggregate normally used in such construction.The invention particularly relates to an improvement in two of the knownmethods for building roads by the so-called cold laying process in whichthe bituminous binding agent is used in the form of a powder; Accordingto the cold laying method described in Radcliffe, U. S. Patent1,655,240, which has been reissued as U. S. Patent Re. No. 17,985 underdate of March 3, 1931, the stone aggregate is first coated with a slowdrying liquid binder and then with a powdered bituminous binder and themixture is later amalgamated on the road by rolling. In this method noheat is employed either to melt the bituminous substance or to effectamalgamation on the road. The solvent liquid binder employed issufficiently fluid at atmospheric temperatures so that no heat isapplied either to liquefy the binder or during admixture with theaggregate. The powdered bituminous binder is of sufliciently highmelting point so that when it is commingled with the liquid binder theresultant blend will have a desired melting point sulficiently high toresist summer heat. According to the cold laying method described in theBeckwith U. 8. Patent No. 2,220,670, dated November 5, 1940, the stoneaggregate is first coated with a substantially nonvolatile, highlyaromatic, non-paraflinic oil which is fluid at atmospheric temperaturesand then with a powdered bituminous binder having a high melting point,and the mixture is likewise later amalgamated on the road by rolling.

It is to be noted that both of the :above processes have one thing incommon in that the aggregate is first coated with a solvent liquidbinder which is fluid at atmospheric temperatures and then with apowdered bituminous binder. Thus a manufacturer of paving material usingeither of the two above mentioned methods would obviously batch into asuitable mixer three separate components in the following sequence:first, the mineral aggregate; second, the liquid solvent binder; andthird, the powdered bituminous binder.

My invention relates to an improvement in the above mentioned coldlaying methods for building roads and the like. In the aforementionedmethods considerable dimculty has. been experienced in obtaining auniformly good end product and the following disadvantages are manifest:(l) The paving mixtures are too slow in obtaining initial stabilityexcepting under a considerable amount of pneumatic tired trafiic. (2)The mixtures are highly susceptible to stripping in the presence ofwater. (3) Longer mixing time is required to make this material becausethe two bituminous components i. e., the solvent liquid binder and thepowdered bituminous binder have to be introduced into the mixer insequence and not simultaneously, thus the mixer man requires more timeto mix a batch of material, (4) Paving mixtures made at atmospherictemperatures of say 50 F. can not be successfully coated with the samequantity of-total binder :as can ice identically graded aggregates madeat temperatures of approximately F. This is due to the fact that as thetemperature at time of mixing is low the solvent liquid binder depositsa thicker film on each aggregate particle than it would if thetemperature were much higher. This temperature variation at time ofmixing from time to time results in non-uniform appearing batches ofpaving material and quite frequently at low temperatures leaves thelarger sized aggregate particles partially or totally uncoated. Forillustration let us say that a certain aggregate composition by reasonof its surface area, porosity, etc., should require a total bituminousbinder of say 6% by weight and that the blending chart indicates that byusing 3% of solvent liquid binder and 3% of powdered bituminous hinderthe composite binder will have a resultant penetration of about at 77 F.If mixing takes place while the atmospheric temperature is around 90 R,we will find that we obtain a uniform and well coated aggregate. Howeverif the mixing takes place at temperatures around 50 F. we will find thata considerable amount Of the larger sized aggregate particles areuncoated. (5) A fairly high percentage of the bituminous binder iscompletely wasted as it does not come into complete submergence with thesolvent liquid binder and it remains in the mixture as just so muchinert material. For example 1 have taken samples of paving materialsmade from the aforementioned process and placed them in a water filledcontainer and after shaking the container found a considerable amount ofpowdered bituminous binder floating on the surface of the water. It isonly fair to relate that paving mixtures made by either of the twoaforementioned methods, if manufactured and consolidated on the roadbed, under ideal working conditions will provide a highly satisfactoryroad surfacing material.

It is the object of my invention to provide a simple and effective coldlaying process that will completely obviate the disadvantages of the twoaforementioned processes and still retain most of their desirablefeatures. Other objects of my invention will appear from the followingdescription of my discovery.

In practicing my invention for building roads I first of all prepare aunique composite liquid bituminous binder. This composite binder may betermed to be an oleosol and may be conveniently made in any suitablemixing chamber preferably provided with power stirrers and a variablespeed motor and is made in the following manner: First, a substantiallynon-volatile bituminous flux oil, hereinafter fully described, in anamount equal to from 20% to 60% of the total composite binder is placedin the mixing chamber. Thereupon a substantially volatile liquidsolvent, hereinafter fully described, in an amount equal to from 10% to50% of the total composite binder is likewise placed in the mixingchamber and the power stirrers operated. This produces a nonviscoussolvent liquid flux oil cutback. The making of this liquid flux oilcutback will require but a few minutes. Subsequent to the aboveoperation, a powdered bituminous binder, hereinafter fully described, inanamount equal to from 10% to 50% of the total composite binder isslowly added to the mixing chamber while the power stirrers are kept incontinuous operationand the mixing continued until the three :abovementioned components result in a very slightly viscous but still readilypumpable composite liquid containing a fairly high percentage of thepowdered bituminous binder particles suspended in the liquid flux oilcutback in a state of solid or semi-solid condition. At this point mycomposite liquid bituminous I reduce the spread of the power drivenstirrers in the mixing chamber. After the stone aggregate material hasbeen thoroughly coated with approximately 4% to 12% by weight, dependingof course on the surface area, porosity etc., of the aggregatecomposition, with my composite liquid bituminous binder the mixture maybe taken to the road bed and spread to the desired cross section andthickness and consolidated by rolling.

The above described paving material will exhibit a high initialstability and the composite liquid bituminous binder will, concurrentlywith the evaporation of the volatile solvent liquid it contains, rapidlyamalgamate to provide a substantially homogeneous bituminous binder forthe stone aggregate material.

The substantially non-volatile bituminous flux oil I have chosen to useas my first component of my composite liquid bituminous binder may beany one of several grades of asphaltic road oil or bituminous liquidfuel oils. It may be a substantially non-volatile, non-parafiinic,highly aromatic lubricating oil extract as that term is understood inthe industry. Preferably this flux oil or liquid binder should have aviscosity S. S. F. of between 30 to 100 at 122 F.

The substantially volatile liquid solvent 1 have chosen to use as mysecond component of my composite liquid bituminous binder is a petroleumdistillate and may be, depending on the type of finished product I wishto produce, a gas, oil or light fuel oil, kerosene, diesel, naphtha etc,it being obvious that each type of solvent has a different evaporationrate and solvent power. Depending on the solvent used, I can produce acomposite liquid bituminous binder having, slow, medium or rapid curingcharacteristics.

The powdered bituminous binder I have chosen as the third component ofmy composite liquid bituminous binder should preferably meet thefollowing general requirements:

Specific gravity 1.00 Softening point (R. & B.) 250-300 Penetration at77 F -5 Flash 450 min.

The powdered bituminous binder may be prepared from natural asphalt suchas gilsonite or from petroleum asphalt, and can easily be reduced to thedesired fineness by means of a suitable impact mill, as for example a#14 Williams Hammer Mill. I have found that I can obtain very goodresults by reducing the hard asphalt to about the following degree offineness:

Mesh 100% passing 30 60% passing 80 40% passing 100 20% passing 200 Inmaking my composite liquid bituminous hinder or oleosol it is essentialthat the components be commingled at or near normal atmospherictemperatures so as to not completely dissolve all of the powderedbituminous binder particles contained in the liquid flux oil cutback asthis would produce a material too viscous to pump readily or coat themineral aggregate particles properly. In actual practice I usually makeup just enough composite liquid bituminous binder for the following daysmixing operation as it is apparent that the above described compositebinder will progressively become more viscous as the powdered bituminousbinder is being slowly dissolved by the solvent liquid flux oil cutback.

As specific examples of some of the many composite liquid binders I havemade, the following table indicates the percentage by weight of eachcomponent, the approximate residue after evaporation of the volatileliquid solvent and the approximate resultant penetration of the residueat 77 F.

T he composite liquid bituminous binder above described provides abinder that is easily pumpablc at normal temperatures and one that isreadily miscible with stone aggregate materials without employing anyheat whatsoever. When suitable well graded aggregate is fully coatedwith the above composite binder and the mixture is spread to the desiredthickness on the road bed and subsequently consolidated into place byrolling an excellent pavement is obtained. My process difiiers from thetwo aforementioned methods for building roads in that my powderedbituminous binder is commingled with the liquid solvent binder prior tocontact with the stone aggregate and is not introduced into the mixer asa separate component.

As a variant to making a three component composite liquid bituminousbinder as hereinbefore described I sometimes use liquid flux oilcutbacks such as slow curing, medium curing or rapid curing types. Thesegrades of cutback asphalt are well known to the industry as SCs, MCs andRC grades of liquid asphalt, and as they con tain a substantiallyvolatile liquid solvent it is necessary to add little if any additionalsolvent liquid, therefore I introduce any one of these grades of cutbackliquid asphalts into my mixing chamber with or without the addition ofmore liquid solvent and then slowly add to the mixing chamber a quantityof powdered bituminous binder as hereinbefore described, and continuethe mixing until I have my composite liquid bituminous binder. Igenerally prefer to use an 80-0, MC-O or RC-O as these grades have aFurol viscosity of 75-150 at 77 F. and as a consequence are readilypumpable at the normal atmospheric temperatures.

The above description of my invention is not to be considered aslimiting my invention but only as illustrative of the invention, as manyvariations may be made within the scope of the following claims.

I claim:

1. A process for making material for roads wherein stone aggregate iscoated with a composite liquid bituminous binder consisting essentiallyof a pumpable suspension of powdered hard asphalt in a non-viscous fluxoil cutback, which comprises blending a substantially non-volatilehighly aromatic, non-parafiinic flux oil with a volatile petroleumdistillate to form said non-viscous flux oil cutback, mixing therewithat atmospheric temperature said powdered hard asphalt, discontinuing themixing when the mixture starts to become viscous so as to produce saidcomposite liquid bituminous binder, and mixing said composite liquidbituminous binder with said stone aggregate at atmospheric temperature;the proportions of the various materials being such that the powderedasphalt, flux oil, and petroleum distillate comprise 10 to 50%, 20 to60%, and 10 to 50% by weight respectively, of the composite liquidbituminous binder, and the composite liquid bituminous binder comprisesapproximately 4 to 12% by weight of the aggregate composition.

2. A process according to claim 1 in which the nonvolatile liquid is ahighly aromatic lubricating oil extract.

3. A process according to claim 1 in which the powdered asphaltcomprises a fines fraction which is smaller than 100 mesh and a coarsefraction which is larger than 80 mesh.

References Cited in the file of this patent 5 UNITED STATES PATENTS 6Richardson Jan. 10, 1911 Berger June 5, 1928 Ferguson Sept. 20, 1932Fletcher Dec. 19, 1933 Baskin Apr. 30, 1935 Wells Aug. 6, 1935 SwanbergFeb. 9, 1937 Greaves et a1. Apr. 13, 1954

1. A PROCESS FOR MAKING MATERIAL FOR ROADS WHEREIN STONE AGGREGATE ISCOATED WITH A COMPOSITE LIQUID BITUMINOUS BINDER CONSISTING ESSENTIALLYOF A PUMPABLE SUSPENSION OF POWDERED HARD ASPHALT IN A NON-VISCOUS FLUXOIL CUTBACK, WHICH COMPRISES BLENDING A SUBSTANTIALLY NON-VOLATILEHIGHLY AROMATIC, NON-PARAFFINIC FLUX OIL WITH A VOLATILE PETROLEUMDISTILLATE TO FORM SAID NON-VISCOUS FLUX OIL CUTBACK, MIXING THEREWITHAT ATMOSPHERIC TEMPERATURE SAID POWDEREC HARD ASPHALT, DISCONTINUING THEMIXING WHEN THE MIXTURE STARTS TO BECOME VISCOUS SO AS TO PRODUCE SAIDCOMPOSITION LIQUID BITAMINOUS BINDER, AND MIXING SAID COMPOSITE LIQUIDBITUMINOUS BINDER WITH SAID STONE AGGREGATE AT ATMOSPHERIC TEMPERATURE;THE PROPORTIONS OF THE VARIOUS MATERIALS BEING SUCH THAT THE POWDEREDASPHALT, FLUX OIL, AND PETROLEUM DISTILLATE COMPRISE 10 TO 50%, 20 TO60%, AND 10 TO 50% BY WEIGHT RESPECTIVELY, OF THE COMPOSITE LIQUIDBITUMINOUS BINDER, AND THE COMPOSITE LIQUID BITUMINOUS BINDER COMPRISESAPPROXIMATELY 4 TO 12% BY WEIGHT OF THE AGGREGATE COMPOSITION.